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University of California Publications in Zoology 



FIG. 22. Lateral views of the right mandibles of (A) Iguana delicalissima {MCL 60823) and (B) 

 Amblyrhynchus cristatus (RE 1396), showing differences in the relative heights of the dentary (den) and 

 surangular (sur) and in the position of the row of mental foramina (mf). Scale equals 1 cm. 



this study, all have a relatively larger splenial than Sauromalus. Therefore, I consider a 

 small splenial to be apomorphic for iguanines. 



The anterior inferior alveolar foramen pierces the mandible on its lingual surface at a 

 point between one-third and one-half the way back from the anterior end of the jaw (Fig. 

 23). In most iguanines, this foramen lies within the suture between the splenial and the 

 dentary at the anterior end of the splenial or along its anterodorsal edge. The coronoid may 

 extend anteriorly between splenial and dentary so that it forms the posterior margin of the 

 anterior inferior alveolar foramen (Fig. 23A) in some Brachylophus, Dipsosaurus, and 

 Sauromalus. Varying amounts of this anterior extension of the coronoid may be covered 

 by the splenial lingually, excluding the coronoid from the border of the foramen (Fig. 

 23B). This condition occurs in Conolophus, Ctenosaura, Iguana, most Cyclura, and in 

 some Brachylophus, Dipsosaurus, and Sauromalus. In Brachylophus, the splenial is 

 truncated, and the anterior inferior alveolar foramen sometimes lies entirely within the 

 dentary. In Amblyrhynchus, the coronoid extends far anteriorly, and the foramen lies 

 between it, rather than the dentary, and the splenial (Fig. 23C). 



